Valves are known. Known valves include a stem threaded into a bonnet and the bonnet inserted into a body. Known valves also include packing external to the threads of the stem and a packing nut threaded onto the bonnet. The packing nut compresses the packing and creates a seal. Known valves further include a bonnet nut threaded onto the body. The bonnet nut retains the bonnet within the body. Difficulties can arise in preventing rotation of and locking the bonnet within the body when the bonnet is threaded into the body and/or when a sealing member is internal to the threads of the stem.